We have 2 of those in our house.
I found the safest way to clean (less odor later) is baking soda - I
make a paste of it with water, apply it with a hand held brush and rinse
it off by turning on your shower.
This method is also good for those soap scums around the tub.
This would be safe for your children and anyone that has allergies to
I would just give it a good cleaning as suggested above. After all
it's just a kids bathroom and if you put something nice in it they are
just going to wreck it.